Palestinians have insisted that the attack was carried out by far-right-wing Israeli nationalists in revenge for the murders of three Israeli teens. Israeli police had said they were exploring all possibilities, from an act by Jewish extremists to a Palestinian honor killing.

Palestinian Attorney General Muhammad Abd al-Ghani Uweili said Saturday that a preliminary autopsy of Abu Khdeir's body revealed that he had breathed in smoke â?? proof that he was alive when his body was set on fire.

Mohammed's cousin, a 15-year-old Palestinian-American, was injured during clashes with Israeli security forces last week. On Sunday, he was sentenced to nine days of house arrest, police spokeswoman Luba Samri said. Tariq Abu Khdeir, who lives in Florida but was visiting family here, will remain at a home in the east Jerusalem neighborhood of Beit Hanina.

Tariq's family says he was severely beaten by Israeli police during protests in Jerusalem last week. The incident is under investigation.

When the news of Sunday's arrests broke Sunday afternoon, Israelis took to social media to express shock and disgust that a fellow Jew could commit such a heinous crime.

"This is not our way, and the criminals who performed this heinous act brought disgrace upon the Jewish people and the state of Israel," Avalon said. "They must be brought to justice and prosecuted to the full extent of the law, as an example to others. Israel and the Jewish people's strength is based on the Jewish morals and values."

Jody Garfinkle, a Jerusalem mother of four told USA TODAY that "if these people are in fact the perpetrators of this horrible and inhuman crime they should be thrown in jail with no possibility of parole. Any person that would kill another human being and burn them to death is nothing other than a psychopath and does not belong in society."

Rahel Jaskow, a Jewish resident of Jerusalem, took a similar view. "Whoever they are, whatever their motive - if they are guilty, I wish them exactly the same thing I wish the killers of our own three boys: justice, swift and strong," Jaskow said. "If, in some parallel universe, I were the judge - Jewish or not - and the suspects were found guilty and were members of my own people, I would sentence them twice: once for the act itself, and a second time for dishonoring our people."

Prime Minister Benjamin Netanyahu said that Israel would act calmly and responsibly in the face of rising Israeli-Palestinian hostilities, just hours after Israel's military carried out airstrikes on 10 sites in Gaza.

The strikes killed seven Hamas members early Monday in the southern Gaza town of Rafah along the Egyptian border, the Islamist group told Reuters news agency.

The Israeli airstrikes targeted what the army said were militant sites including rocket launchers and a weapons manufacturing site, following at least 29 other rockets and mortar shells fired from the Gaza Strip at Israel over the weekend.

Two of those rockets were aimed at Beersheba, a southern city deeper into Israel than any other attack in the current round of violence. The military said its "Iron Dome" defense system intercepted the two rockets.

Tensions have been high since the three Israeli teens were abducted on June 12. The Israelis blamed Hamas for their killings and launched a major crackdown against the Islamic militant group.

Protests spread over the weekend from Jerusalem to Arab towns in northern Israel, with hundreds of people throwing rocks and fire bombs at officers who responded with tear gas and stun grenades, according to Israeli police. Samri said 22 Arab Israelis were arrested in clashes on Saturday.

Israeli Arabs, unlike Palestinians in the West Bank and Gaza, hold citizenship rights. But they often face discrimination and many identify with the Palestinians. Even so, violent riots like those that occurred on Saturday are rare.

Clashes mostly subsided by early Sunday, but the situation remained tense. Samri said a Jewish woman was attacked and lightly wounded early Sunday by a group of Palestinians in Jerusalem's Old City. Her husband fired his weapon and the attackers fled, and police were searching for them, Samri said.

Tariq's parents, Suha and Salah, said Tariq was the last person with Mohammed shortly before he was seized. They said Tariq left Mohammed to eat before the Ramadan fast began at dawn Wednesday.

Police said Tariq resisted arrest, attacked officers, and was captured with a slingshot for lobbing stones.

His face was masked in a keffiyeh, an Arab headscarf that some Palestinian protesters wore during the clashes to conceal their identity, police added. He was detained along with six other protesters, police said, including some armed with knives, adding that several officers were hurt in that specific protest, one of many that day.

Amateur video of what Tariq's father, Salah, said was the beating aired on a local television station, and he said he could recognize his son from his clothing.

The U.S. State Department said it was "profoundly troubled" by reports of his beating and demanded an investigation. Israel's Justice Ministry quickly launched a formal investigation.

Ron Dermer, the Israeli ambassador to the U.S., said Sunday, "It's unacceptable in our system if police use excessive force."

He told Fox News Sunday that the teen was "not just an innocent bystander who was pulled off a schoolyard. He was with six other people. They were masked. They threw petrol bombs and Molotov cocktails at our police. Three of them had knives, from what I understand. That does not excuse any excessive use of force, and our justice ministry is opening an investigation."

In the West Bank, the army arrested a Palestinian in the city of Hebron. His family identified him as Hossam Dufesh. The army would not elaborate on the arrest, but Israeli forces have concentrated its search for the killers of three Israeli teens in the Hebron area.